Patent application title: HIGH-PERFORMANCE ULTRASONIC TRANSDUCER AND METHOD FOR THE PRODUCTION THEREOF

Abstract:

The invention relates to an ultrasonic transducer, comprising an
ultrasonic flange and a magnetostrictive driver, wherein the driver is
connected to a contact surface of the ultrasonic flange that faces the
same, and wherein the driver and the ultrasonic flange are connected in
the region of the contact surface by means of electron beam welding
and/or laser beam welding. The contact surface is configured by the
bottom of at least one receiving pocket, which receives the end of the
driver on the ultrasonic flange side, and at least one receiving pocket
is configured in a pedestal-like elevation of the end of the ultrasonic
flange facing the driver, and the pedestal-like elevation is higher than
the depth of the receiving jackets configured therein.

Claims:

1. An ultrasonic transducer comprising:an ultrasonic horn and a
magnetostrictive driver,wherein the driver is joined to a contact face of
the ultrasonic horn proximal thereto,wherein the driver and the
ultrasonic horn are joined in a zone of the contact face by electron-beam
welding and/or laser-beam welding,wherein the contact face is formed by
the bottom of at least one receiving pocket, which accommodates the end
of the driver proximal to the ultrasonic horn,wherein the at least one
receiving pocket is formed in a pedestal-like elevation of an end of the
ultrasonic horn proximal to the driver, andwherein the height of the
pedestal-like elevation is greater than the depth of the at least one
receiving pocket formed therein.

2. An ultrasonic transducer according to claim 1, wherein the driver
comprises exactly one magnetostrictive element.

3. An ultrasonic transducer according to claim 1, wherein the driver
comprises a plurality of magnet plates.

4. An ultrasonic transducer according to claim 1, wherein there are
provided a plurality of receiving pockets, in each of which part of the
driver or of the magnet plates is accommodated.

5. An ultrasonic transducer according to claim 1, wherein the ultrasonic
horn and/or the magnetostrictive material of the driver is subjected at
least in part to a heat treatment.

6. An ultrasonic transducer according to claim 1, wherein the ultrasonic
horn is constructed in two pieces, wherein the contact face is formed on
an intermediate part of the ultrasonic horn, which part is joined to the
other part of the ultrasonic horn.

7. An ultrasonic transducer according to claim 1, wherein the ultrasonic
horn comprises a first ultrasonic horn, the ultrasonic transducer further
comprises a second ultrasonic horn, which is joined to the driver on a
side thereof distal to the first ultrasonic horn, wherein the driver and
the second ultrasonic horn are joined in the zone of a contact face of
the second ultrasonic horn by means of electron-beam welding and/or
laser-beam welding.

8. A method for creating a permanent joint between an ultrasonic horn and
a magnetostrictive driver of an ultrasonic transducer, comprising:joining
the driver and the ultrasonic horn in the zone of a contact face of the
ultrasonic horn proximal to the driver by electron-beam welding and/or
laser-beam welding, andforming the contact face by the bottom of at least
one receiving pocket, which accommodates the end of the driver proximal
to the ultrasonic horn,wherein the at least one receiving pocket is
formed in a pedestal-like elevation of the end of the ultrasonic horn
proximal to the driver,wherein the height of the pedestal-like elevation
is greater than the depth of the receiving pocket formed therein,
andwherein the electron or laser beam is aligned or guided in such a way
that it enters through the side bounding wall of the pedestal-like
elevation into the monolithic ultrasonic horn at the height of the
contact face and parallel thereto.

9. A method according to claim 8, wherein the driver is formed by a
plurality of magnet plates, and wherein the electron or laser beam,
during the welding operation, is always aligned parallel to the contact
face as well as parallel to the lines of contact between the magnet
plates and the contact face.

10. A method according to claim 8, wherein the electron and/or laser beam
is guided over the joint zone in such a way that a first part of the
welded joint is created from a first side and a second part of the welded
joint is created from a second side.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001]This application is a continuation of PCT/EP2009/001186, filed on
Feb. 19, 2009, which claims priority to DE Application No. 10 2008 010
617.8, filed on Feb. 22, 2008, the contents of each being incorporated
herein by reference.

FIELD OF THE INVENTION

[0002]The present invention relates to an ultrasonic transducer comprising
an ultrasonic horn and a magnetostrictive driver, wherein the driver is
joined to a contact face of the ultrasonic horn proximal thereto, as well
as to a method for creating a permanent joint between the ultrasonic horn
and the driver of such an ultrasonic transducer.

BACKGROUND OF THE INVENTION

[0003]In the prior art of electronic transducers, either piezoelectric or
magnetostrictive drivers are used as drivers for the desired ultrasonic
vibration. The former have the advantage of high efficiency but the
disadvantage of limited output power, due to the low tensile strength of
piezoelectric materials. In contrast, higher output power can be
generated with magnetostrictive ultrasonic transducers, but in this case
the disadvantages of relatively lower efficiency, greater waste heat
during operation and a more complex construction or a more expensive
production method have to be taken into consideration.

[0004]One problem in the design of magnetostrictive ultrasonic transducers
is that the magnetostrictive material must be joined appropriately to the
ultrasonic horn, such a joint usually being produced in the prior art by
means of a soldering method, especially a hard soldering method.

[0005]Generic magnetostrictive ultrasonic transducers of the aforesaid
type are known, for example, from WO 2004/105085 A1 and WO 2006/055368
A2.

[0006]In these ultrasonic transducers, the driver consists of a large
number of plates of magnetostrictive material (referred to hereinafter as
magnet plates), which are fixed in recesses of the ultrasonic horn or to
a surface of the ultrasonic horn by means of a hard soldering method. A
suitable geometry of the magnet plates makes it possible to energize the
plates with an alternating magnetic field. For this purpose the
ultrasonic transducers described in the aforesaid publications are
equipped, for example, with a central aperture in the magnet plates and a
suitable coil arrangement, with which the two legs of the magnet plates
bounding the aperture can be excited to vibrations in the ultrasonic
frequency range by passing an appropriate current through the coil and in
this way using the magnetostriction effect. These vibrations are then
transmitted by the magnet plates to the ultrasonic horn and passed on
inside the ultrasonic horn to its vibrating head. However, the
disadvantages of magnetostrictive ultrasonic transducers already
mentioned above also exist in this prior art.

[0007]Furthermore, from DD 59963 A there is known a method for joining
electromechanical transducers with coupling elements and implements of
ultrasonic generators, wherein the laminated core of a magnetostrictive
transducer is joined to a plane end face of the ultrasonic generator by
means of electron-beam welding in order to achieve coupling with the
lowest possible loss. In this case high energy is needed for the electron
beam, in order to weld the laminated core to the end face over the entire
area thereof. In addition, this joining technique proves to be not
particularly stable, since the laminated core is held exclusively against
the plane face.

[0008]Finally, EP 0468125 A2 also discloses an ultrasonic horn in which
two contiguous portions are joined to one another by means of
electron-beam welding or laser-beam welding.

SUMMARY

[0009]Against this background, it is the object of the present invention
to provide an ultrasonic transducer of the type mentioned in the
introduction with improved characteristics. Furthermore, the present
invention relates to a method for producing a permanent joint between the
ultrasonic horn and magnetostrictive driver of such an ultrasonic
transducer.

[0010]For this purpose, it is provided according to the invention--in
addition to the features already mentioned in the introduction--that the
driver and the ultrasonic horn are or will be joined in the zone of the
contact face by means of electron-beam welding and/or laser-beam welding,
wherein the contact face is formed by the bottom of at least one
receiving pocket, which accommodates the end of the driver proximal to
the ultrasonic horn, wherein the at least one receiving pocket is formed
in a pedestal-like elevation of the end of the ultrasonic horn proximal
to the driver, and wherein the height of the pedestal-like elevation is
greater than the depth of the receiving pocket formed therein.

[0011]In the inventive method, it is provided in addition to the aforesaid
features that the electron or laser beam is aligned or guided in such a
way that it enters through the side bounding wall of the pedestal-like
elevation into the monolithic ultrasonic horn at the height of the
contact face and parallel thereto.

[0012]In connection with the present invention, it has proved in
particular that non-negligible proportions of the problems of
magnetostrictive ultrasonic transducers as mentioned in the introduction
are caused by the soldered joint provided between driver and ultrasonic
horn in the prior art, and so an ultrasonic transducer according to the
invention or produced according to the invention is characterized by,
among other features, higher efficiency, less waste heat and a large
number of further advantages, to be discussed in more detail hereinafter.

[0013]As the first advantage of an inventive ultrasonic transducer, it may
be pointed out that the method of electron-beam welding or of laser-beam
welding employed according to the invention in the zone of the contact
face opens up the possibility that the ultrasonic horn, the contact face
of the ultrasonic horn and/or the magnetostrictive material of the driver
can be subjected to separate heat treatments before the inventive welded
joint is created, specifically without subsequently destroying the
associated advantages once again or adversely influencing them during
subsequent creation of a permanent joint between driver and ultrasonic
horn.

[0014]In contrast, the method of hard soldering known from the prior art
is associated with the disadvantage that the temperatures in the range of
approximately 750° C. needed for hard soldering adversely alter,
once again, the material microstructure, created beforehand by laborious
heat treatment, of the ultrasonic horn and/or of the magnetostrictive
material of the driver, and so the advantages of previous heat treatment
of the said elements are no longer fully realized in the finished
ultrasonic transducer. In the case of electron-beam welding or laser-beam
welding, on the other hand, the thermal stress on the ultrasonic
transducer is less and is limited to a much smaller zone--even in
comparison to other welding methods.

[0015]Furthermore, it was found in connection with the present invention
that the method of electron-beam welding or laser-beam welding provided
according to the invention guarantees better transmission of the acoustic
vibrations from the driver to the ultrasonic horn. In this regard, it may
be assumed that the solder material (referred to as solder) used for
soldering in the prior art causes a large damping effect on the acoustic
vibrations in the zone of the joining point. Thus the efficiency of an
inventive ultrasonic transducer is high compared with the prior art.

[0016]In addition, better mechanical strength of the completed joint is
assured by application of the joining technique provided according to the
invention. This has a positive effect on the fatigue limit of an
inventive ultrasonic transducer and in particular also leads to a greater
load capacity of the joining point between driver and ultrasonic horn.
Not only is the possibility of use under higher loads opened up thereby
but also greater flexibility is achieved in terms of the exact layout of
the joining point in view of the acoustic vibration conditions over the
length of the ultrasonic transducer.

[0017]In turn, a further aspect of the present invention, not adequately
considered in the known prior art, is based on the circumstance that a
large zone around the actual joining point was exposed to a high
temperature during soldering or hard soldering (approximately 750°
C. during hard soldering), whereas this is not the case in electron-beam
welding or laser-beam welding. In this regard it must be pointed out that
the magnetostrictive material of the driver of an inventive ultrasonic
transducer is preferably equipped with an insulating layer, which often
becomes damaged over a large area by exposure to the temperatures
necessary for soldering, in turn potentially leading, for example, to
short circuits between adjacent elements of the driver. In contrast,
during electron-beam welding or laser-beam welding according to the
present invention, the height of the weld--needed to join the driver to
the ultrasonic horn and formed transversely along the contact face--is
advantageously limited to a value of approximately 1-2 mm, thus greatly
reducing the damage to insulating layers on the magnetostrictive material
of the driver.

[0018]Furthermore, yet another advantageous effect is evident in
connection with the present invention. Since a meltable metal alloy was
always employed as bonding material in the soldering methods used in the
prior art, the magnet plates forming the driver were contacted in large
zones around the contact face by the conductive solder or were
short-circuited with one another and with the contact face of the
ultrasonic horn. This leads to greater electrical losses during
electromagnetic excitation of vibrations and ultimately to greater heat
generation in the zone of the joining point during operation of an
ultrasonic oscillator. This adverse effect can be reduced with the
present invention, since only a relatively small joint zone is created in
the zone of the outermost edge of the driver during electron-beam or
laser-beam welding, especially when this is performed along the contact
face between ultrasonic horn and driver, as in the present case. Cooling
devices that formerly were difficult to construct for the ultrasonic
transducer can therefore be constructed more easily or can even be
completely omitted.

[0019]The techniques of electron-beam or laser-beam welding applied in
connection with the present invention--either alternately or if necessary
in succession (for example, also at different locations)--are known as
such, and so detailed explanations in this regard are unnecessary.
However, it must be pointed out that it is possible in both cases to
create welds having a predetermined depth, which is adequate in
connection with the present invention. This is obvious, especially in
view of the particularly advantageous circumstance that the contact face
where the inventive welded joint is to be created is sometimes not
directly accessible.

[0020]Furthermore, it is provided in connection with the present invention
that the contact face along which the welded joint between the edge of
the driver and the contact face of the ultrasonic horn will be created is
formed by the bottom of at least one receiving pocket, which accommodates
the end of the driver proximal to the ultrasonic horn. In this
connection, the term receiving pocket is to be advantageously understood
as a recess, adapted to the contour of the driver or magnetostrictive
elements, in the side of the ultrasonic horn proximal to the driver.

[0021]During electron-beam or laser-beam welding, seam depths sufficiently
large for the present purpose can be produced for the weld to be created,
and so the electron or laser beam used for creation of the welded joint
can be guided and adjusted in such a way that it creates the required
welded joint through an edge zone of the monolithic ultrasonic horn in
the zone of the bottom of a receiving pocket serving as the contact
face--and in fact does so without causing a short circuit of adjacent
magnetostrictive elements in zones above the actual weld or an unwanted
change of the material microstructure in large zones around the actual
joining point or area.

[0022]Advantageously, the electron or laser beam is directed sideways onto
the ultrasonic horn, parallel to and at the height of the contact face
formed by the bottom of the receiving pocket, whereby the driver bearing
against the ultrasonic horn at the corresponding height in the at least
one receiving pocket is welded to the bottom of the receiving pocket in
the zone of its contact face.

[0023]Furthermore, in the inventive ultrasonic transducer, it is provided
that the at least one receiving pocket is formed in a pedestal-like
elevation of the end of the ultrasonic horn proximal to the driver.
Although the term pedestal-like elevation is used here, it may also be
constructed by machining down a zone of the ultrasonic horn surrounding
the receiving pocket.

[0024]This decisively facilitates the welding operation provided according
to the invention, especially when it is additionally provided, as is the
case in connection with the present invention, that the height of the
pedestal-like elevation is greater than the depth of the receiving pocket
formed therein.

[0025]Hereby the electron or laser beam oriented preferably parallel to
the contact face during welding can be guided in such a way that, from
the outside, it enters a side bounding wall of the pedestal--which has a
reduced cross section--at approximately the height of the contact face,
whereby the necessary penetration depth for the electron or laser beam
can be further reduced, as can the energy input associated therewith,
including the adverse effects on the material microstructure adjacent to
the weld. Specifically, the beam has to travel only a shorter path
through the monolithic ultrasonic horn in order to reach the actual joint
zone between driver or magnet plates and ultrasonic horn.

[0026]Conceivable materials for the (at least) one ultrasonic horn and the
magnetostrictive driver are the materials known for this purpose from the
prior art, and, in the case of the ultrasonic horn--which may be
subjected to various loads depending on its intended use--include in
particular aluminum, titanium, various steels and especially also
nickel-based alloys (such as Nimonic 80A; see DIN 2.4952). As material
for the driver, it is possible in principle to use all kinds of
magnetostrictive materials, although obviously those with high
magnetostriction capacity are to be preferred. Examples in this category
are FeCo alloys or terbium-containing alloys, such as the alloy families
known under the generic names of Hiperco, Terfenol and Gerfenol.

[0027]It must be pointed out expressly at this place that the
magnetostrictive driver--which can be excited to vibrations with a
suitable coil arrangement--of an inventive ultrasonic transducer can be
constructed in the most diverse geometries from one or more
magnetostrictive elements, as long as it is then suitable for transducing
ultrasonic energy and in connection with the invention can be welded at
least at the edge or end face to a contact face of the ultrasonic horn
proximal thereto.

[0028]In particular, it is possible in a preferred configuration of the
invention to provide that the driver is composed of only one single
magnetostrictive element (for example, in the form of a plate or bar).

[0029]In a further preferred configuration of the invention, however, it
is possible to provide that the driver as the magnetostrictive element
comprises a plurality of magnet plates as magnetostrictive elements,
while simultaneously avoiding the disadvantages that result in this
connection in the prior art.

[0030]In a preferred configuration of the inventive method, it is possible
to provide additionally, in the case of a driver composed of a plurality
of magnet plates, that the electron or laser beam guided over the entire
joint zone is aligned not only parallel to the contact face but also is
always parallel to the lines of contact between the magnet plates and the
contact face on the ultrasonic horn. The said line of contact is defined
by the linear extent of the edge of the respective magnet plate bearing
on the contact face. This alignment of the beam leads to further
minimization of the short circuits occurring between adjacent magnet
plates in the weld zone.

[0031]In order also to further reduce the temperature load or energy
input, which in any case is low in comparison with the prior art, in the
weld zone, it may be further provided that the electron and/or laser beam
is guided over the joint zone in such a way that a first part of the
welded joint is created from a first side and a second part of the welded
joint is created from a second side, preferably the opposite side.
Thereby the penetration depth of the electron or laser beam necessary for
creation of a sufficiently stable welded joint can be substantially
halved, and so the edge of the driver or the edge of the magnetostrictive
elements bearing on the contact face--in the imaginary lines through the
actual joint zone--can advantageously be welded to the contact face of
the ultrasonic horn firstly from one side to approximately the middle (or
slightly beyond), after which the other part or the other half is welded
from the opposite side.

[0032]In connection with the invention, there are preferably provided
several receiving pockets, in each of which part of the driver or of the
magnet plates (in the form of laminated cores if necessary) is
accommodated. Hereby the bonding of the driver to the ultrasonic horn is
further improved in terms of stability of the joint.

[0033]Finally, an already mentioned aspect of the present invention
materializes if, in a further preferred improvement of the invention, the
ultrasonic horn and/or the magnetostrictive material of the driver is
subjected at least in part (for example, only in zones relevant for this
purpose) to a (separate) heat treatment.

[0034]The high-power ultrasonic transducers provided according to the
invention are suitable in principle for any desired intended uses of
ultrasonic transducers, although in view of the inventive advantages it
is possible in particular to conceive of applications with high loads
(such as use of the ultrasonic transducer for treatment of liquid fossil
fuels or other liquids). Consequently, preliminary heat treatment of the
ultrasonic horn, if appropriate only in the zone of the contact face(s)
subjected to the particular loads and/or of the vibration head, which is
distal relative to the driver and also highly loaded, may prove
advantageous. Even in the case of the driver it may be advantageous to
apply preliminary heat treatment, since hereby it may be possible in
particular to optimize the magnetostrictive characteristics of the
material being used. Besides, the heat treatment leads to an insulating
oxide layer on the surface of the magnet plates, whereby the magnet
plates, which preferably bear upon one another in stacks, are insulated
from one another. As already explained, the joining techniques known from
the prior art suffered from the problem, noticed in connection with the
present invention, that the material microstructure or the
magnetostrictive characteristics of the heat-treated material or the
oxide layer or a separately applied insulating layer on the surface of
the magnetostrictive elements of a driver were destroyed or adversely
influenced by a high heat load being input into large zones (for example,
during hard soldering). In contrast, this adverse effect (reduction of
the strength of the horn or strength and magnetostrictive characteristics
of the driver; short circuits between the magnet plates due to
destruction of the insulating layer) does not occur at all or at worst
occurs in a locally limited zone during the electron or laser beam
welding method used according to the invention, and so the already
mentioned advantages of the invention are also manifested in this
respect.

[0035]Furthermore, it must be pointed out that an ultrasonic horn of an
inventive ultrasonic transducer does not necessarily have to be
constructed in one piece, but instead it may be constructed in multiple
pieces, especially two pieces. Thus, in yet another preferred
configuration of the invention, it may be provided that the contact face
is formed on an intermediate part of the ultrasonic horn, which part is
joined (for example by screwed connection) to the other part of the
ultrasonic horn.

[0036]And finally it must be pointed out that the present invention also
comprises an ultrasonic transducer that comprises one magnetostrictive
driver and in total two ultrasonic horns disposed on different sides of
the driver. In this case, an inventive welded joint between the driver
and the respective ultrasonic horn must then be provided on both sides of
the driver in the zone of the respective contact face of the ultrasonic
horn.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037]The invention will be explained in more detail hereinafter on the
basis of several exemplary embodiments illustrated in the drawing,
wherein:

[0038]FIG. 1 shows a perspective view of a first exemplary embodiment of
an inventive ultrasonic transducer,

[0039]FIG. 2 shows a first longitudinal section through the ultrasonic
transducer of FIG. 1 parallel to the plane spanned by the magnet plates,

[0040]FIG. 3 shows a second longitudinal section through the ultrasonic
transducer of FIG. 1 perpendicular to the plane spanned by the magnet
plates,

[0041]FIG. 4 shows an intermediate piece of a second exemplary embodiment
of an inventive ultrasonic transducer,

[0042]FIG. 5 shows a perspective view of a third exemplary embodiment of
the present invention,

[0043]FIG. 6 shows a perspective view of a fourth exemplary embodiment of
the present invention, and

[0044]FIG. 7 shows a perspective view of a fifth exemplary embodiment of
the present invention.

DETAILED DESCRIPTION

[0045]The first exemplary embodiment of an inventive ultrasonic transducer
1, illustrated in FIGS. 1 to 3, comprises a heat-treated ultrasonic horn
2 and a driver 3, which for reasons of clarity is illustrated only
partly, can be energized by means of a plurality of coils not
illustrated, functions on the principle of magnetostriction and is
composed of a large number of magnet plates 4, which are grouped into six
stacks 9 in total (only one being illustrated here). Magnet plates 4,
which are made of a magnetostrictive material and have also been heat
treated, bear with their edge 5 proximal to ultrasonic horn 2 on a
contact face 6, in the illustrated exemplary embodiment each contact face
6 being formed respectively by the bottom 7 of a receiving pocket 8,
which is rectangular in overhead view. In total, there are provided six
receiving pockets 8, in each of which, in the finish-assembled ultrasonic
transducer 1, there is accommodated the end of a stack 9 of a plurality
of magnet plates 4, each stack in the present exemplary embodiment being
composed of twenty-two magnet plates, each 0.4 mm thick. It is
self-evident that a smaller or larger number of magnet plates or
different plate thicknesses may also be used.

[0046]Receiving pockets 8 are formed in a pedestal-like elevation 10,
whose height H (see FIG. 2) is greater than the depth T (see FIG. 3) of
receiving pockets 8. To create the inventive joint between driver 3
formed from magnet plates 4 and ultrasonic horn 2, an electron beam can
be aligned or guided in such a way according to arrows E1 and E2 that it
enters the monolithic ultrasonic horn sideways, or in other words through
side bounding wall 11 of pedestal-like elevation 10, at the height of
contact face 6 (see dashed line 12 in FIG. 2) and parallel thereto.
Instead of an electron beam, however, a laser beam that can be
appropriately focused and has sufficient energy may be used to create an
inventive welded joint in connection with the present invention.

[0047]In the illustrated ultrasonic transducer 1, the electron beam, which
is always aligned parallel to the line of contact between a magnet plate
and the ultrasonic horn (as is evident from FIGS. 1 and 2), is first
directed from one side according to arrow E1 onto ultrasonic horn 2 or
side wall 11 of pedestal-like elevation 10, during which the penetration
depth, which can be adjusted by the energy of the electron beam being
used, of the electron beam is to be chosen such that it penetrates into
the material, with sufficient energy to produce a permanent welded joint,
approximately as far as the middle of edge 5 of the respective magnet
plate 4 bearing on contact face 6. In the process, the electron beam is
guided according to arrow F1--in an alignment that is always parallel to
arrow E1--linearly over the joint zone, so that all magnet plates 4
accommodated in the six receiving pockets 8 are welded linearly to
ultrasonic horn 2 at least as far as the middle of contact face 6 or 7.

[0048]Thereafter a corresponding welding operation is repeated from the
other side of magnet plates 4. For this purpose, the electron beam, with
constant alignment, is guided according to arrow E2 over the joint zone
(see arrow F2), with the effect that all magnet plates 4 are welded along
their edges to ultrasonic horn 2 upon completion of the described
process. If necessary, it would also be possible to guide the electron
beam in the inverse direction compared with the course illustrated
according to arrow F2, for example if the simultaneous use of two
electron and/or laser beams directed onto the joint zone from different
sides is being considered for creation of the welded joint.

[0049]The ultrasonic vibration imposed by means of driver 3 can then be
transmitted effectively via the electron-beam-welded (or
laser-beam-welded) joint zone to the ultrasonic horn, where it is
amplified by constriction 13 of horn 2 and transmitted to ultrasonic head
14, which is then excited to vibration according to double arrow A.

[0050]Ultrasonic horn 2 is provided with a circumferential fastening
flange 15, with which it can be fastened, for example, to an external
structure. A node point of the vibration transmitted in longitudinal
direction through ultrasonic horn 2 is suitable as an attachment point
for flange 14.

[0051]Finally, FIG. 4 further illustrates that the zone of ultrasonic horn
2 provided with contact face(s) 6 may be constructed if necessary in the
form of an intermediate piece 16, which is joined to the other part of
the ultrasonic horn (not illustrated)--for example by a screwed
connection. For this purpose, in the illustrated example, intermediate
piece 16 is advantageously provided on its underside with a threaded pin
17 having a male thread, not illustrated, with which a screwed connection
can be made with a corresponding female thread on the other part of the
ultrasonic horn. In this case also magnet plates 4, grouped into a total
of six stacks 9 (of which only one is illustrated once again and, for
simplicity, only stack 9 as a whole is illustrated here) and forming
driver 3, are welded by an electron beam or laser beam, at their edge
proximal to intermediate piece 16 of the ultrasonic horn, in the zone of
a contact face 7 of intermediate piece 16 formed by the bottom of
receiving pockets 8, to this ultrasonic horn. As in the previous
exemplary embodiment, receiving pockets 8 are formed in a pedestal-like
elevation 10 of the end (formed in this case by intermediate piece 16) of
the ultrasonic horn proximal to driver 3.

[0052]FIG. 5 shows a third exemplary embodiment of an inventive ultrasonic
transducer, which is composed of one driver 3 and two ultrasonic horns 2,
2', wherein the two ultrasonic horns 2, 2' are disposed in opposite
orientations on opposite sides of the driver--which is composed of six
stacks 9 of magnet plates, just as was the case hereinabove--and are
respectively welded thereto in the way already described in the
foregoing. Here also it would be possible, for example, for the
respective end zone of the two ultrasonic horns 2, 2' proximal to the
driver to be formed by an intermediate piece, which is joined to the
other part of the ultrasonic horn.

[0053]FIG. 6 shows a fourth exemplary embodiment of an inventive
ultrasonic transducer comprising ultrasonic horn 2 and driver 3, wherein
driver 3 is composed of exactly one magnetostrictive element 18 in the
form of a bar, which again is accommodated at one end in a receiving
pocket 8, adapted to the round cross section and disposed in a
pedestal-like elevation 10 on ultrasonic horn 2, and therein is welded to
ultrasonic horn 2 in the zone of the contact face formed by the bottom of
receiving pocket 8. For this purpose a laser or electron beam can be
directed according to arrow E3 onto side bounding wall 11 of the
pedestal-like elevation and (for example by rotating the ultrasonic
horn)--while ensuring that its alignment is kept parallel to the contact
face at the height thereof and is always directed radially onto the
midpoint of the round cross section--can be guided according to arrow F3
around pedestal-like elevation 10 (see dashed line 19), with the effect
that here also a first part of the welded joint is created from a first
side and a second part of the welded joint is created from a second side
of the ultrasonic horn, with a penetration depth of the electron or laser
beam extending preferably to only approximately the middle.

[0054]And, finally, FIG. 7 shows yet a fifth exemplary embodiment of the
invention, again with two ultrasonic horns 2, 2' (with construction
identical to that of FIG. 6) and a driver 3 disposed between them and
composed of a single bar-shaped magnetostrictive element 18. The
difference compared with the ultrasonic transducer illustrated in FIG. 6
is that, on side 20 of driver 3 distal to first ultrasonic horn 2 there
is disposed a further ultrasonic horn 2'--of design identical to that of
first ultrasonic horn 2--which is welded to this driver in the already
described way. In the examples according to FIGS. 6 and 7 also, it is
possible for the zone of the ultrasonic horn proximal to the driver to be
constructed if necessary in the form of a separate intermediate piece.